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1. Field of the Invention
The invention relates to a composition for preventing sweat-related odor by interfering with different steps of the odor-producing course, particularly by the inhibition of the androgen receptor expression and human odorant carrier proteins.
2. Description of the Related Art
Formation of body odor especially axillary odor results mainly from exceptional odor-producing abilities in the areas of body. These abilities include the following:
1) There arc increased apocrine sweat glands in these areas, which are comprised of ducts that open directly into the hair follicle and become functional at puberty. It is known that there is a high level of 5alpha-reductase activity in human apocrine glands of which type-1 5alpha-reductase is predominant. 5alpha-reductase converts testosterone (T) to dihydrotestoserone (DHT) and may play a central role in the apocrine gland development and function from the beginning of puberty. The androgen receptor levels were also found to be high in the apocrine gland of patients with osnidrosis. These observations indicate that the activity of androgens is involved with the functions of apocrine sweat glands.
2) Sweat secreted from apocrine sweat glands contains numerous substances, which are most likely the precursors for forming odoriferous compounds, even although these precursors are odorless. These precursors mainly consist of (1) volatile odor-producing steroids such as dehydroepiandrosterone (DHEA), 5xcex1-androst-16-en-3-one (androstenone), and 5xcex1-androst-16-en-3xcex1-ol (adrostenol); (2) nonvolatile steroid sulfates such as dehydroepiandrosterone sulfate (DHEAS), which can be bacterially converted to odorous adrostenol; (3) volatile short-chain fatty acids, especially (E)-3-methyl-2 hegemonic acid (E-3M2H), and cholesterol esters. It is demonstrated that E-3M2H is presented in far greater quantities than volatile odoriferous steroids in apocrine secretions (700:1), although both have similar olfactory thresholds; and (4) sulfur-containing amino acids. Apocrine gland cells may take up these precursors from serum and/or enzymatically formed in apocrine gland cells.
3) Odorless apocrine precursors are transported to the skin surface by odorant carrier proteins. A main odor-producing precursor E-3M2H can be carried to the skin surface by binding to apolipoprotein D (apoD). ApoD is expressed in apocrine sweat glands as an apocrine secretion odor-binding protein (ASOB2). ASOB2 is glycoprotein and found to be glycosylated for their functions. Some of androgens such as dihydrotestosterone (DHT) can significantly increase the expression of apoD.
4) Odorless apocrine precursors carried onto the skin surface interact with the microflora in areas of body such as the underarm to cause the characteristic odor. It is demonstrated that the nature and intensity of malodor correlate with microbial populations and counts, At least two different kinds of Gram-positive bacteria metabolize odorless precursors to be odoriferous substances. Lipophilic diphtheroids cause the steroid odor by metabolizing androstenone, if the population of micrococci is staphylococcus epidermis, the odor of isovaleric acid could be apparent because of metabolizing fatty acid. Some anaerobic Gram-negative bacteria may also contribute to malodor by using sulfur-containing amino acids to generate the volatile sulfur-containing compounds (VSC). In general, mixed odor of the steroids and short-chain fatty acids may characterize the axillary region.
Deodorant products in the market are typically based on three principles to control body odor, especially in the underarm regions: (1) reduce perspiration; (2) inhibit bacterial growth; and (3) cover malodor. These products show that they have some effects on reducing unpleasant body odor. However they still have considerable disadvantages. First, effective period of these products is very limited. For example, an active component in commercial products for reducing perspiration is aluminum salt, which blocks the sweat gland ducts and only causes a 50% of perspiration reduction. Antimicrobial agents in these products reduce the number of microorganisms on the surface of the local skin. However the effect obtained with the antimicrobial agents are easily reversed by the recovery of microflora numbers. Next, the active components in the products often cause irritation, burning, itching, and other uncomfortable sensations to some people with sensitive skin. Lowering the amounts of active components in the products may reduce irritation but it may also result in impaired efficiency. Therefore, there remains a need for improved products.
An ideal composition for preventing sweat-related odor should be able to: (1) maximally attenuate functions of the apocrine sweat glands including gland development, maintenance and secretion; (2) reduce uptake and formation of odor-producing precursors; (3) reduce transport of odor-producing precursors to skin surface; (4) block apocrine gland ducts to decrease sweating moisture on the skin surface; (5) inhibit bacteria activities including suppression of enzymatic metabolites which may convert: the odorless precursors to odoriferous substances; and (6) prevent possible irritation of skin. A deodorant composition with these functions would be more potent, safer, and long-lasting.
This invention is based on the finding that the sweat-related odor is produced mainly through an increase in the odor-producing precursors from the apocrine gland and consequent transport of odor-producing precursors to skin surface to for in malodor after interacting with the microflora. According to this invention, it has been found that a composition, when topically applied to body parts such as the underarm, prevents sweat-related odor by interfering with the odor-producing course. This invention is capable of attenuating functions of the apocrine sweat glands, reducing sweating moisture on the skin surface and bacteria activities. This invention may be more specifically regarded as inhibiting transport of odor producing precursors to the skin surface.